Dam



Jan. 5, 1954 u. FINSTERWALDER ET AL 2,664,714

DAM

Filed Jan. 15, 1952 horizontal foundation.

Patented Jan. 5, 1954 DAM Ulrich Finsterwalder and Philipp Ebert,

Muenchen, Germany, assignors to Dyckerhofi & Widma'nnKommanditgesellschaft, Muenchen, Germany, a German company ApplicationJanuary 15, 1952, Serial No. 266,468

3 Claims. 1

This invention relates to an arched or vaulted retaining wall for dams.

It isthe object of the present invention to improve the arch effectespecially in low dams and dams of average height so as to transmit alarger part of the hydraulic pressure to the slopes of the valley bysuch arch effect.

The invention will be best understood and further objects will appearfrom a study of the following detailed description taken in connectionwith the accompanying drawing, with the understanding, however, that theinvention is not confined to any strict conformity with the showing inthe drawing, but may be changed and modified as long as such changesmark no material departure from the salient features of the invention asexpressed in the appended claims.

Fig. 1 is a development of the dam, viewed from the air side,

Fig. 2 is a top plan view of the dam,

Fig. 3 is a section on line III-III in Fig. 2, on a larger scale, and

Fig. 4 is. a section on line IV-IV .of Fig. 3, on a still larger scale.

Solid dams are built substantially on two different constructionalprinciples, i. e. either as a gravity dam or as an arched or vaulteddam. The gravity dam hangs over its foundation, so to speak, while thevaulted dam bears on the slopes of the valley. Since in vaulted dams theforces are transmitted by vault pressure to a solid foundation formed bythe slope of the valley, such dams have a higher degree of safety thangravity dams. The latter is exposed to shearing and bending stresses andon principle is seated on a In spite of these undeniable advantagesarched dams can be used only where the local conditions are particularlyfavorable. This is due to the fact that in order to ensure the settingup of an arch effect, elastic yielding of the arch is required which isimpeded by the connection of the dam with its foundation. Thus an archeddam acts only partly as an arch, while partly its acts as an arm hangingover the foundation as in case of a gravity dam.

Moreover, the crown of the dam is stressed to a small extent only by thehydraulic pressure acting upon it and, therefore, will be flexed by asmall amount only in the direction of the hydraulic pressure while muchlarger deflections are occurring, for instance, in the middle of theheight of damming. Thus the arm projecting from the ground is supportedby a bearing at the top end. As a result, bending stresses are caused inthe central part of the dam, producing tensile 2 stresses on the airside of the dam, and at the point of fixation bending stresses withtension on the water side are set up.

On the point of fixation the tensile stresses can be avoided by anenlargement directed towards the air side which enlargement is shaped inaccordance with the course of the moment taken about the point offixation. In the central point of the dam the tensile stresses due tobending can be taken only by a thickening extending over the wholeheight of the wall. This, however, would again act to restrict the totalvault effect, so that in the end a wall or dam laterally projecting fromthe foundation would again be obtained. These difficulties are avoidedby my novel construction in which through-gaps are provided in the toppart of the dam, at suitable intervals, whereby this part of the dam isprevented from transmitting compressive stresses in a peripheraldirection and hence cannot act as a vault.

The extension of the gaps in a vertical direction is defined by thecondition that the upper part of the dam has to act as a gravity damwith respect to the hydraulic pressure. It was found to be particularlyadvantageous to provide gaps having a vertical extension equalling aboutthe 1.5 fold amount of the thickness of the wall.

By the provision of the radially extending gaps according to the presentinvention the hydraulic pressure bearing against the upper part of thedam and the appertaining bending moment is introduced into the vaulteddam at the upper edge of the same. Bythis stress the dam is bentbackwards at this spot in a favorable manner whereby the moments settingup bending stresses on the air side in the central part of the dam aresubstantially reduced. Moreover, a vertical compression is exerted onthe vaulted part of the dam by the part of the dam acting as a gravitydam, whereby the capacity of taking bending moments is increased.

Referring now to the drawing, it will be seen that 2 and 3 are theabutments by which the wall bears on the two slopes of the valley. Thearched retaining wall or dam is vertical and is of uniform thickness inits crown I and middle part 4. Only the base part 5 is enlarged andconstructed in the form of an abutment of corbel in such a way that thebearing pressure in the filled state of the basin is directedperpendicularly to the bottom joint.

Basing on the knowledge that an arch effect would be detrimental in theupper part of the wall, the head part I of the wall is provided withgaps or slits 6 which are radially directed, i. e.

they extend in the direction of the radius of curvation of the dam.

Preferably the gaps are spaced from each other by intervalscorresponding to the conventional width of the sections of work providedfor laying the concrete in building a retaining dam, as shown in Fig. 2.The gaps may be formed by conventional methods in working the concrete.In a vertical direction the gaps B extend over a height correspondingapproximately to the 1.5 fold amount of the thickness of the wall at thecrown, Figs. 1 and 3. 7

It will be understood that bythese gaps 6 the hydraulic pressure loadingon the upper part of the wall and the appertaining bending moment areintroduced into the arched wall at the upper border of the same. Thusthe wall isbent back at this point in a favorable manner, whereby themoments producing bending stresses in the middle part of the Wall on theair side are substantially reduced.

The gaps 6 are stopped or made tight against passage of water in themanner which is known for such purposes. In the example illustrated thepacking of each gap comprises a strip 1, e. g., of copper sheetextending over the whole height of the gap. The copper sheet may consistof several interconnected parts, if desired.

'Thepacking strip 1 has a fold 8 projecting into the gap 6 while itsbent ends are anchored in t wall is prevented from transmitting anycompressive stresses and hence from acting as an arched wall, the heightof the same is theoretically reduced by the height of the gaps. In

this reduced height the valley to be barred by I .the dam as a rule issubstantially narrower than at the top of the dam, so that the Wall canbe made with a smaller radius. The upper part of the dam acts as agravity wall. Its horizontal thrust acts to bend the upper zone of thewall to the air side in a favorable manner, whereby the maximum bendingmoment in a vertical direction, with tension stress on the air side, isreduced and displaced downwards to a point or plane where the loadbearing thereon is heavier.

While the invention has been described in detail with respect to a nowpreferred example and embodiment of the invention it will be understoodby those skilled in the art after understanding the invention thatvarious changes and modifications may be made without departing from thespirit and scope of the invention and it is intended, therefore, tocover all such changes and modifications in the appended claims.

What is claimed is:

1. In an arc-shaped dam particularly for the control of flood waters aplurality of vertical spacedly adjacent recesses in the crest portion ofthe dam, said recesses extending in the radial direction of the damcrest from its one face to its opposite face, the size and the number ofsaid recesses being controlled to prevent the dam crest to transmitcompression stresses in the peripheral direction of the dam and means toclose the said recesses.

2. An arc-shaped dam according to claim 1, said recess closure meansconsisting of resilient metal plates vertically extending through theheight of said recesses from the dam crest to thebottom thereof andtraversing the said recesses.

3. An arc-shaped dam according to claim 2, the height of the saidrecesses equalling to 1.5 times the thickness of the dam crest.

ULRICH FINSTERWALDER.

PHILIPP EBERT.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,529,141 Danel Nov. 7, 1950

